1. Field of the Invention
The present invention relates to an ink jet recording head and a method for manufacturing the same.
2. Description of the Related Art
FIGS. 9A and 9B are appearance perspective views schematically showing a color cartridge 100 that is an ink jet recording head. FIG. 9A is a view from beneath. FIG. 9B is a view from above. The color cartridge 100 includes a supporting member 109 and a lid 110 that define a recording liquid chamber that holds recording liquid. A recording element substrate 101 for discharging recording liquid droplets and an electric wiring substrate 102 are attached to the supporting member 109.
FIGS. 10A and 10B are schematic views of the recording element substrate 101. FIG. 10A shows the side of the recording medium (the face). FIG. 10B shows the side of the supporting member 109 (the back). FIGS. 11A and 11B are schematic views of a bonding surface 115 of the supporting member 109 to which the recording element substrate 101 is bonded. FIG. 11A shows the bonding surface 115 before applying adhesive 104 thereto. FIG. 11B shows the bonding surface 115 after applying adhesive 104 thereto.
The area around supply paths 106 of the supporting member 109 and the upper surfaces of partition walls 108 between the supply paths 106 constitute the bonding surface 115. Adhesive 104 is applied to the bonding surface 115. The back of the recording element substrate 101 is bonded to the bonding surface 115 of the supporting member 109 with the adhesive 104 therebetween. Recording liquid is supplied from the recording liquid chamber through the supply paths 106 to recording liquid supply ports 105 formed in the recording element substrate 101. The supplied recording liquid is caused to form bubbles by heating elements (not shown) formed in the recording element substrate 101, is discharged through discharge ports 103, and lands on a recording medium.
If the back of the recording element substrate 101 is insufficiently bonded to the bonding surface 115 of the supporting member 109 and the gap therebetween is insufficiently sealed, recording liquid can leak through the gap. Therefore, adhesive 104 must be applied to the entire bonding surface 115 so that the gap between the recording element substrate 101 and the bonding surface 115 of the supporting member 109 can be sealed with the adhesive 104.
Japanese Patent Laid-Open No. 2006-212902 discloses a supporting member having V-shaped grooves formed in portions of a bonding surface of the supporting member that come into contact with regions surrounding recording liquid supply ports of a recording element substrate when the back of the recording element substrate is bonded to the bonding surface of the supporting member. The grooves hold adhesive and prevent lines of adhesive from breaking, thereby improving the sealing performance between the recording element substrate and the bonding surface of the supporting member.
From the standpoint of cost, workability, and so forth, the supporting member 109 is formed by molding. Since the supporting member 109 is formed by molding, the flatness of the bonding surface 115 is not so high. So, the recording element substrate is fixed in the following way.
First, lines of adhesive 104 are drawn on the bonding surface 115 of the supporting member 109 using a dispenser (not shown). The recording element substrate 101 the position and attitude of which are adjusted with a high degree of accuracy is brought into contact with the adhesive 104 at a predetermined height, for example, 70 μm above the bonding surface 115. This state is maintained until the adhesive 104 is cured. Thereafter, the area around the recording element substrate 101 and the electric connecting portions of the recording element substrate 101 are sealed with sealant, the sealant is thermally cured, and the recording element substrate 101 is thereby fixed.
In this way, the recording element substrate 101 can be bonded and fixed regardless of the flatness of the bonding surface 115 of the supporting member 109. However, in this way, the recording element substrate 101 is fixed, while floating in the adhesive 104. If the surface of applied adhesive 104 is not uniform in height and is partially less than 70 μm high, the adhesive 104 cannot perfectly come into contact with the recording element substrate 101, and seal failures can occur. Therefore, when applying adhesive 104, it is necessary not only to draw unbroken lines of adhesive 104 but also to stabilize the height of the surface of adhesive 104.
FIGS. 12A to 12C are schematic views showing adhesive 104 applied to the bonding surface 115 of the supporting member 109.
FIG. 12A shows the bonding surface 115 of the supporting member 109 to which adhesive 104 is applied. The adhesive 104 is also applied to the partition walls 108 in order to seal the gap between the area around the supply paths 106 of the supporting member 109 and the area around the recording liquid supply ports 105 of the recording element substrate 101. FIG. 12B is an enlarged view of the part XIIB of FIG. 12A. The pattern of applied adhesive 104 has rounded corners 117. Near the corners 117 are a region c where surface tension γ concentrates and a region d where surface tension γ disperses. The layer of adhesive 104 is thick in the region c where surface tension γ concentrates and thin in the region d where surface tension γ disperses. That is to say, the layer of adhesive 104 is thick on the center lines of the partition walls 108, and particularly at the intersection of the center lines. In contrast, the area around the thick portion is relatively thin. This makes the surface of adhesive 104 uneven as shown in FIG. 12C. In low portions such as the region d, the adhesive 104 can be out of contact with the back of the recording element substrate 101. In such a case, the gap between the recording liquid supply ports 105 of the recording element substrate 101 and the supply paths 106 of the supporting member 109 is insufficiently sealed, and it is highly likely that recording liquid leaks and sealant enters. If the amount of application is increased to thicken the layer of adhesive 104, it is likely that the adhesive 104 falls into the supply paths 106 of the supporting member 109 and climbs up from the recording liquid supply ports 105 of the recording element substrate 101 to the discharge ports 103. This lowers the margin with respect to the height of the surface of applied adhesive, and as a result, lowers productivity.